Strasburg (13-5) walked four in his outing, but only allowed one hit and one run over six frames to earn the victory. He struck out six.

Sean Burnett and Ryan Mattheus each hurled a perfect inning in relief, while Craig Stammen gave up two hits in a scoreless ninth.

Ryan Zimmerman belted a two-run homer, Michael Morse added a solo shot and Steve Lombardozzi went 4-for-5 with four runs scored for NL East-leading Washington, which has won 17 of its last 21 games.

"I don't think any of us are satisfied, we still have our best baseball ahead of us," Strasburg said.

Trevor Cahill (9-10) was charged with four runs on six hits and three walks over six innings in defeat. Arizona was coming off a 6-4 road trip.

The only hit allowed by Strasburg was a two-out, run-scoring single by Chris Johnson in the fourth. Strasburg had walked two earlier in the inning, which was delayed for several minutes after home plate umpire Dale Scott took a foul ball off his mask.

C.B. Bucknor, the third-base umpire, took over behind the plate for the remainder of the game.

Johnson's hit momentarily tied things, 1-1, before Zimmerman took Cahill deep into the left-field seats in the fifth. Lombardozzi singled ahead of the two- out blast.

Morse sent one even further when he cranked a towering shot to straightaway center leading off the sixth.

Lombardozzi, who tripled and scored on Bryce Harper's sacrifice fly in the third, crossed the plate again in the seventh when the Diamondbacks committed an error on a potential inning-ending double play ball.

The Nats added four more in the ninth off Mike Zagurski. Harper plated one with a sacrifice fly, Adam LaRoche chipped in an RBI two-bagger and Jayson Werth capped a three-hit night with a two-run double.

"We didn't have a lot of energy to overcome [the deficit] today," Diamondbacks manager Kirk Gibson said. "We have to play a lot better to beat them."

Game Notes

Morse was working on an 18-game hitting streak coming in, but major league officials informed the Nationals earlier Friday that Morse's only hit in a game against the Phillies on August 2 was reversed to an error on Cole Hamels. He has now hit in eight straight...Before the game, Arizona placed pitcher Josh Collmenter on the 15-day disabled list with ulcers and recalled pitcher Brad Bergesen from Triple-A Reno...Arizona is 3-40 when scoring three runs or less.